package com.superbit.service.util;


import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base32;
import org.apache.commons.codec.binary.Base64;

import com.superbit.core.exception.ParamInvalidException;

/**
 * @function 谷歌验证器校验类
 * @author WangZhenwei
 *
 * @version 2017年3月25日 下午1:57:28
 */
public class GoogleAuthUtils {
	
	// taken from Google pam docs - we probably don't need to mess with these  
    private static final int SECRET_SIZE = 10;  
      
    private static final String SEED = "g8GjEvTbW5oVSV7avLBdwIHqGlUYNzKFI7izOF8GwLDVKs2m0QN7vxRs2im5MDaNCWGmcD2rvcZx";  
      
    private static final String RANDOM_NUMBER_ALGORITHM = "SHA1PRNG";  
      
    int window_size = 3; 
    
    public void setWindowSize(int s) {  
        if (s >= 1 && s <= 17)  
            window_size = s;  
    }  
      
   
    /**
     * 校验谷歌验证码是否有效
     * @param codes  校验码
     * @param savedSecret  保存的秘钥
     * @return
     */
    public static Boolean authcode(String codes, String savedSecret) {  
    	if(!GoogleAuthUtils.isLong(codes)){
    		return false;
    	}
        long code = Long.parseLong(codes);  
        long t = System.currentTimeMillis();  
        GoogleAuthUtils ga = new GoogleAuthUtils();  
        ga.setWindowSize(1);  
        boolean r = ga.check_code(savedSecret, code, t);  
        return r;  
    }  
    
    /**
     * 初始化获取私钥，传入user
     * @param testUser
     * @return
     */
    public static String genSecret() {  
        String secret = GoogleAuthUtils.generateSecretKey();  
        return secret;  
    }  
    
    private static String generateSecretKey() {  
        SecureRandom sr = null;  
        try {  
            sr = SecureRandom.getInstance(RANDOM_NUMBER_ALGORITHM);  
            sr.setSeed(Base64.decodeBase64(SEED));  
            byte[] buffer = sr.generateSeed(SECRET_SIZE);  
            Base32 codec = new Base32();  
            byte[] bEncodedKey = codec.encode(buffer);  
            String encodedKey = new String(bEncodedKey);  
            return encodedKey;  
        }catch (NoSuchAlgorithmException e) {  
        }  
        return null;  
    }  
      
   /**
    * 获取二维码参数
    * @param user
    * @param host
    * @param secret
    * @return
    */
    public static String getQRBarcodeURL(String email, String secret) {  
    	String host = "BitStar";
        String format = "otpauth://totp/%s:%s?secret=%s&issuer=%s";  
        return String.format(format, host, email, secret,host);  
    }  
      
    /**
     * 校验谷歌验证码正确性，内部方法，根据私钥，验证码和时间进行校验
     * @param secret
     * @param code
     * @param timeMsec
     * @return
     */
    private boolean check_code(String secret, long code, long timeMsec) {  
        Base32 codec = new Base32();  
        byte[] decodedKey = codec.decode(secret);  
        long t = (timeMsec / 1000L) / 30L;  
        for (int i = 0; i <= window_size; ++i) {  
            long hash;  
            try {  
                hash = verify_code(decodedKey, t + i);  
            }catch (Exception e) {  
                return false;
            }  
            if (hash == code) {  
                return true;  
            }  
        }  
        return false;  
    }  
      
    private static int verify_code(byte[] key, long t) throws NoSuchAlgorithmException, InvalidKeyException {  
        byte[] data = new byte[8];  
        long value = t;  
        for (int i = 8; i-- > 0; value >>>= 8) {  
            data[i] = (byte) value;  
        }  
        SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1");  
        Mac mac = Mac.getInstance("HmacSHA1");  
        mac.init(signKey);  
        byte[] hash = mac.doFinal(data);  
        int offset = hash[20 - 1] & 0xF;  
        long truncatedHash = 0;  
        for (int i = 0; i < 4; ++i) {  
            truncatedHash <<= 8;  
            truncatedHash |= (hash[offset + i] & 0xFF);  
        }  
        truncatedHash &= 0x7FFFFFFF;  
        truncatedHash %= 1000000;  
        return (int) truncatedHash;  
    }  
    
    public static void main(String[] args) {
    	String key = genSecret();
    	System.out.println(key);
    	boolean b = authcode("479261","LSJ6HZXYCB7CITPL");
    	String a = getQRBarcodeURL("280738120@qq.com","KHEJDTVSEK4UOQGN");
    	System.out.println(a);
    	System.out.println(b);
	}

	/**
	 * @function 判断对象是否是Long类型
	 * @param str
	 * @return
	 */
	private static boolean isLong(String str) {
		try{
			validateIsLong(str, null);
			return true;
		}catch(Exception e) {
			return false;
		}
	}
	
	/**@function 字符串不是Long类型时抛出异常
	 * @param str
	 * @throws ParamInvalidException
	 */
	private static void validateIsLong(String str, String paramName)throws ParamInvalidException {
		try{
			Long.parseLong(str);
		}catch(Exception e) {
			throw new ParamInvalidException(paramName, "Not Long");
		}
	}
}
